Impregnated paper article



juiy 30, 1935. w H, WOODFQRD 2,009,465

IMPREGNATED PAPER ARTI OLE Filed Feb. 14, 1935 WATSON H.WoonFoRD terial.

Patented July 30, 1935 K 2.00am

- UNITED STATES PATENT OFFICE- IMPREGNATED PAPER ARTICLE Watson H. Woodford, Bridgeport, Conn.,' assignor to Remington Arms Company, Inc., a corpora- This invention relates tion of Delaware Application February 14, 1933 Serial No. 656,682

15 Claims.

to the manufacture of paper tubes for shot shell bodies, and contemplates certain improvementsin the matter of penetrating said tubes with a waterproofing ma- The present application is a continuation-in-part of the inventorsprior application, Serial No. 527,506, filed April 3,1931.

Shot shell tubes are wound from a specially prepared paper which is texture. The paper is of a somewhat porous ordinarily supplied in edge of the sheet which is to form the outside of the tube is usuallycolored with a suitable coloring material and is preferably formed of a separate layer.

The entire sheet may be built up of asmany as five separate layers of pulp, and the layer which forms the outside wrap and receives the coloring matter is made from a finer grain fibre which'produces' a more dense paper. The outer part or section of the outside wrap of each tube is thus much more dense and less permeable than theremainder of the tube.

In preparation for use such tubes are usually coated :with a heat absorbent, such as parafiin wax, castor oil or other suitable material, which penetrates the paper and prevents burning and charring thereof during shot propelling powder.

the combustion of the When a shot shell is fired the combustion of the powder produces for a brief interval a condition of a high temperature and high pressure, and burning powder grains movingat high velocity will penetrate and char dry paper to such an extent that the shell body is greatlyweakened, and

may be ruptured either in flringor upon'subsequent extraction from the gun chamber.

It is highly important that shot shells be protected against such charring.

; Acommon method of treatment for this purpose consists in immersing. the tubes in a: bath of the heat absorbent such as parafiin'at a temperature well above the boiling point of water.

In order to secure the proper penetration, the tubes'as placed in the heated bath contain about 8% of moisture, part of which is in the fibres themselves, and the remainder in the inter-fibre spaces. Due to the heat of the bath this moisture is vaporized, and is expelled along with'a quantity of air, both the air and the water being replaced by the heat absorbent.

Due to the greater density of. the outside surface of the tube, the penetration of the heat absorbent is chiefly from the ends and the interior surface, water vapor and air being expelled through the relatively dense exterior surface as the heatabsorbent penetrates from the, interior. This process is very readily observed when the tube'is' placed in a heat absorbent bath within aglass container; gas bubblesv collect on the-exterior surface: in increasing quantities and are eventually released and rise to the surface of the bath. i

As heretofore stated, coloring'matteris usually applied to the relativelydense portion of the sheet which forms the tube exterior. Ifthis coloring matter is a dye, it may not substantially increase the density of the sheet or interfere with the passage of air andlwater vapor there-- through. However; some colors can be secured only by the use of pigments. For example, a desirable and permanent green is best ,obtained 7 from a mixture of Prussian blue and yellow chrome. If the desired color can besecured only by the use of a pigment, such a pigment acts to further increase the density of the already com paratively dense outside. surface with the result that the passage of airand water vapor therethrough in the operation of applying the heat absorbent isrprevented or greatly retarded. It thus becomes very difficult to properly impregnate with a heat absorbent a tube having a-pigment in its surface. Usually only the inside wrap of paper is penetrated, the rest of the wall remaining dry. The expansion of the imprisoned gases may even buckle the inside Wraps of paper, forming an inwardly projecting ridge, and rendering the tube useless. The fact that this' difficulty is due to the failure of the air andwater vapor to be expelled. through the pigmented surface has been demonstrated by slightly abrading parts of the surface or perforatinglthem with a sharp implement... The air can be seen to escape through such an abraded. or perforated surface with an accompanying increased penetrationby the heat, absorbent. f

,It is an object of thisinvention to provide a suitable means for permitting theescape of air and Water vapor from a shell body the exterior surface of which contains a pigment'or'is for any other reason of such a dens'ityas to interfere with the escape of air and water vapor, while leaving the tube in sections each having a con"- tinuous impervious and'unabraded surface.

It has been found that the provision of a. small breaks, cuts,..perforationslor abrasions, spaced and separated by substantial areas of the unbroken and impervious surface, enables the requisite escape of gases, and insures adequate penetration of the tube by the heat absorbent. Such gas passages may be spaced substantial distances, and each may consist of a single cut or abrasion, or a line or group of small cuts, perforations or abrasions. Whether arranged singly or in groups, the gas passages are preferably located on or adjacent to the lines on which the tube is to be cut to form' separate shell bodies. It is a surprising fact that the provision of a very small number of isolated perforations or groups of perforations, separated by relatively large impervious areas, enables the escape of gases from the entire tube wall, and insures effective and uniform absorption of paraffin or other treating fluid. An unperforated tube which has been given the usual paraflin treatment when cut open shows a fair penetration of the inner wrap only and the end portions only of the other wraps, the remainder of thetube paper being substantially dry, whereas a tube with a few isolated cuts or abrasions is thoroughly permeated.

In the drawing:

Fig. 1 is a perspective of a tube embodying one form of the invention.

Fig. 2 is a perspective of a tube including a slightly different embodiment of the invention.

Fig. 3 is a plan view of a sheet of the type used in rolling the tube of Fig. 2, the colored portion of the sheet being shaded.

Fig. 4 is a perspective of a tube embodying another form of the invention.

Fig. 5 is a fragmentary diagrammatic showing of one form of mechanism which may be utilized in the practice of the invention.

Fig. 6 is a fragmentary diagrammatic showing of an alternative mechanism for use in the practice of the invention.

In Figs. 1 and 2 the gas passages in the tube ID are in the form of lines of small perforations ll extending circumferentially of the tube, and preferably on the lines on which the tube is to be cut. Any convenient or desired number of such lines of perforations may be provided; two lines, each spaced from the adjacent end of the tube by the length of two shell bodies, as shown in Fig. 1, are adequate; although four lines, separating the tube into shell body lengths l3 (Fig. 2) may be used. Such perforations may' be formed in various ways; one method comprises the application of a knurling Wheel or wheels to the sheet I4 (Fig. 3) from which the tube is rolled, and particularly to the colored portion l5 of the sheet, which portion forms the outside surface wrap of the tube.

Fig. 4 illustrates a tube in which each isolated gas passage is a single cut, slot or abrasion IS on one side of the tube. One method of forming such abrasions or cuts is to bring a cutting tool or tools against the .tube while the tube is suitably held. If the tube is supported on an arbor l2 (Fig. 5) it may be cut or nicked by the mere pressure of a cutting blade I! which does not move transversely of the tube surface. For this purpose, the usual tube cutting knives may be utilized, neither the tubes nor knives being rotated while the knives are brought against the tube. However, it is sometimes convenient to support the tubes in a substantially semi-cylindrical trough l8 (Fig. 6), and to use one or more rotating cutters to form the gas passages, the tube being held against rotation by friction with the trough, assisted if desired by such means as a spring finger 28.

The pr sent invention is believed to comprise the first discovery that gases'can be expelled from a substantial area of a tube or sheet by the use of small, widely spaced perforations, and the appended claims are to be broadly construed.

What is claimed is:

1. In the manufacture of shot shell tubes, the method of permeating the tube walls with a heat absorbent which comprises the provision of transversely extending lines of perforations in the exterior surface of the tube for permitting the escape of gases during the application of the heat absorbent.

2. In the manufacture of impregnated paper articles having one relatively dense surface, the method of providing for the escape of gases during the impregnating operation which comprises the provision of segregated groups of perforations in said dense surface.

3. In the manufacture of impregnated shot shell tubes having a relatively dense exterior surface, the method of providing for the escape of gases during the impregnating operation which comprises the provision of segregatedgroups of perforations in said dense exterior surface.

4. In the manufacture of impregnated paper articles having one pigmented surface, the method of providing for the escape of gases during the impregnating operation which comprises the provision of segregated groups of perforations in said pigmented surface.

5. In the manufacture of impregnated shot shell tubes, the method of providing for the escape of gases during the impregnating operation which comprises the provision of segregated groups of perforations in one surfaceof said tubes.

6. In the manufacture of shot shell tubes impregnated with a heat absorbent, the method of increasing the penetration of the tube wall by such heat absorbent which comprises the provision of transversely extending lines of perforations in one surface of said tube.

'7. In the manufacture of paper articles impregnated with a heat absorbent, the method of increasing the penetration of the article by such absorbent which comprises the provision of segregated groups of perforations in one surface of said article.

8. A sheet of paper for the manufacture of a shot shell tube comprising a pigmented surface for forming the exterior of said tube and groups of segregated. perforations in said pigmented surface.

9. In the manufacture of shot shell tubes, the method of permeating the tube walls with a heat absorbent which comprises the provision in the surface of the tube of relatively small openings separated byrelatively large impervious areas, said openings permitting the escape of gases during the application of the heat absorbent.

10. In the manufacture of impregnated paper articles having one relatively dense surface, the method of providing for the escape of gases during the impregnating operation which comprises the provision of spaced openings in said dense surface, said openings being separated by relatively large impervious areas.

11. In the manufacture of impregnated shot shell tubes having a relatively dense exterior surface, the method of providing for the escape of gases during the impregnating operation which comprises the provision of spaced openings in said dense exterior surface, said openings being separated by relatively large impervious areas.

12. In the impregnation of a paper article with a fluid medium, the method of providing for the escape of gases from the article during the impregnating operation which comprises the provision in one surface of the article of a relatively small opening or abrasion surrounded by a relatively large impervious area.

13. In the impregnation with a fluid medium of a paper article having one relatively dense surface, the method of providing for the escape of gases during the impregnating operation which comprises the provision in said dense surface of a perforation breaking the continuity of said surface and surrounded by a relatively large unbroken and impervious area.

14. In the impregnation of paper articles with a fluid medium, the method of increasing the penetration of the articles by the medium which comprises the provision of spaced opening in one surface of such articles, said openings being separated by relatively large impervious areas.

15. In the manufacture of rolled paper tubes adapted to be impregnated with a fluid medium, the method of forming spaced openings for the escape of gas during the impregnating operation which comprises applying spaced abrading tools to the tube while the tube is held against rotation.

WATSON H. WOODFORD. 

